Method of straightening sheet metal



UNITED STATES PATENT OFFICE.

METHOD OF STRAl/GHTENING SHEET METAL.

SPECIFICATION forming part of Letters Patent No. 236,853, dated January18, 1881. Application filed August 5, 18H0. (No model.)

To all whom @t may concern:

Be it known that I, GEORGE E. SoMERs, of Waterbury, in the county of NewHaven and State of Connecticut, have invented a new Method ofStraightening Sheet Metal; and I do hereby declare the following, whentaken in connection with the accompanying drawing and the letters ofreference marked thereon,

to be a full, clear, and exact description of the same, and which saiddrawing constitutes part of this specification, and represents asectional view of the dies.

This invention relates to an improvement in the method of straighteningsheet metal. Various devices have been resorted to to remove from sheetmetal the short bends which unavoidably occur therein in the manufactureof the article. In some cases the metal has been rubbed by mechanicaldevices 5 in others it has been drawn through between rolls arrangedafter the manner of a common wire-straightener. ln either case a veryconsiderable amount of power is required to do the work, and the surfaceof the metal is frequently defaced.

The object of this invention is to overcome the difficulties existing inthe methods heretofore practiced; and it consists in the methodhereinafter described, and the dies for performing the same.

A pair of dies, A B, are prepared, their meeting surfacescorrespondingly grooved,\the series of grooves being in` the form of awaved line or succession of curves gradually increasing in extent fromone side to the otherthat is to say, beginning with a short curve at a,the curves enlarging until the extreme curve is formed at the oppositeedge, b, the projecting portions rounded; but the depressed portionsneed not necessarily correspond to the projecting portions, because itis only the projecting portions that are to operate. These dies are inlength made sufficient to take in the sheet of metal required to bestraightened. The two dies are preferably arranged the one stationary,the otherinareciprocating holderas, for instance, in a commonpower-press or other equivalent mechanism; but both may be made toreciprocate, if desired. The arrangement of the dies, however, must besuch that the projections on 'the'one are arranged to strike between theprojections on the other,

and the face of the two parts must be inclined to each other-that is tosay, that the corrugations or ribs will bend the sheet as it enters, andat the opposite edge the ribs will j ust strike the opposite surfaces,as shown in the drawings. Preferably the sheet enters at the finercorrugations, but it may enter from the opposite edge; but in eithercase the dies are arranged relative to each other, as above mentioned,and so that the ribs at one edge necessarily bend the sheet, while theribs at the other edge do not pass beyond the plane of the flat inishedsurface of the sheet. The line drawn through between the dies representsthe sheet. 'lhus arranged, the sheet metal is passed between the dieswhen in operation, and so as to strike the metal, one series of ribs orprojections on one side, and the other series of ribs or projectionsupon the other side, but. between the ribs on the opposite side. Asingle impression would slightly corrugate the metal correspondingto-that is to say, the corrugations be nearly full at the entering-edge,but completely die out at the opposite edge of the dies-the ribs ofthedies; butfas the metal is drawn slowly through between the dies thevarying positions of the ribs, or shortening of the same, make itimpossible that the blows can come in the same relative position uponthe sheet; hence, by this constant succession of blows as constantlyvarying the curve, serves to deliver the sheet metal from the dies in aperfectly ilat and smooth condition.

As the straightening is produced without the usual drawing of the sheet,the friction of such drawing is entirely avoided. The power required toimpart the reciprocating movement to the dies is very much less thanthat required for the usual drawing.

While it is preferred that the ribs or corrugations should be graduallyincreased in eX- tent, so as to make Varyin g distances between theblows struck, a very good result, and much better than by any previousdevice, is accomplishedby arranging the ribs or corrugations equidistantfrom each other. I therefore do not wish to confine this invention tothe varying or gradually-increasing distance between the ribs.

I claim- The herein-described method of straighten- IOO ing sheet metal,consisting in passing the sheet i side bend the sheet, while the ribs atthe other to be straightened between a pair of dies, one edge do notpass beyond the plane of the at lo or both of which have a reciprocatingmoveinishcd surface of the sheet, substantially as ment toward and fromthe other, and provided described. with a series of ribs, the ribs onthe one part GEO. E. SOMERS. intermediate between the ribs on the otherWitnesses:

part, the ribbed face of the two parts inclined to each other, so thatthc ribs at the entering 1 hns. G. Roo'r, NELSON J. WELTON.

